Drives and Controls Magazine

Super motor spins closer to the sea

01 October, 2004

Super motor spins closer to the sea

A prototype 5MW superconducting motor has passed full-load tests under typical operating conditions in the US, bringing the technology a step closer to commercial use in ships. The high-temperature superconductor (HTS) motor, designed by the American Superconductor Corporation, achieved speeds of 230 rpm and delivered 200kNm of torque in the tests conducted at the Florida State University as part of a project sponsored by the US Navy`s Office of Naval Research (ONR).

Ultra-compact HTS motors, weighing one third as much and occupying half the space of conventional copper motors of a similar rating, could revolutionise the propulsion of naval and commercial vessels. They are expected to give ships more space for passengers and cargo, and to cut their running and maintenance costs. In commercial production, they are predicted to cost about the same as conventional motors of a similar torque and power rating.

The latest tests, designed to demonstrate how HTS motors would perform under the stresses and operating conditions of a sea-going vessel, are the final step before proceeding with commercial-scale versions. The photograph (above) shows the 5MW motor (left) during construction, coupled to a conventional 2.5MW motor (right) used to simulate a load. The 5MW machines would be suitable for use in ferries and small cargo vessels.

American Superconductor is also co-developing a 36.5MW, 120 rpm HTS motor under a $70m contract from the ONR. The 75-tonne motor which will produce 2.9MNm of torque, is due to be delivered in the Spring of 2006. By comparison, the two 44MW motors that propel the QE2 liner, each weigh more than 400t.